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edges.rs
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edges.rs
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// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use ich::Fingerprint;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::stable_hasher::StableHasher;
use std::env;
use std::hash::Hash;
use std::mem;
use super::{DepGraphQuery, DepKind, DepNode};
use super::debug::EdgeFilter;
pub struct DepGraphEdges {
nodes: Vec<DepNode>,
indices: FxHashMap<DepNode, DepNodeIndex>,
edges: FxHashSet<(DepNodeIndex, DepNodeIndex)>,
task_stack: Vec<OpenTask>,
forbidden_edge: Option<EdgeFilter>,
// A set to help assert that no two tasks use the same DepNode. This is a
// temporary measure. Once we load the previous dep-graph as readonly, this
// check will fall out of the graph implementation naturally.
opened_once: FxHashSet<DepNode>,
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
pub struct DepNodeIndex {
index: u32
}
impl DepNodeIndex {
pub const INVALID: DepNodeIndex = DepNodeIndex { index: ::std::u32::MAX };
fn new(v: usize) -> DepNodeIndex {
assert!((v & 0xFFFF_FFFF) == v);
DepNodeIndex { index: v as u32 }
}
fn index(self) -> usize {
self.index as usize
}
}
#[derive(Clone, Debug, PartialEq)]
enum OpenTask {
Regular {
node: DepNode,
reads: Vec<DepNode>,
read_set: FxHashSet<DepNode>,
},
Anon {
reads: Vec<DepNode>,
read_set: FxHashSet<DepNode>,
},
Ignore,
}
impl DepGraphEdges {
pub fn new() -> DepGraphEdges {
let forbidden_edge = if cfg!(debug_assertions) {
match env::var("RUST_FORBID_DEP_GRAPH_EDGE") {
Ok(s) => {
match EdgeFilter::new(&s) {
Ok(f) => Some(f),
Err(err) => bug!("RUST_FORBID_DEP_GRAPH_EDGE invalid: {}", err),
}
}
Err(_) => None,
}
} else {
None
};
DepGraphEdges {
nodes: vec![],
indices: FxHashMap(),
edges: FxHashSet(),
task_stack: Vec::new(),
forbidden_edge,
opened_once: FxHashSet(),
}
}
fn id(&self, index: DepNodeIndex) -> DepNode {
self.nodes[index.index()]
}
pub fn push_ignore(&mut self) {
self.task_stack.push(OpenTask::Ignore);
}
pub fn pop_ignore(&mut self) {
let popped_node = self.task_stack.pop().unwrap();
debug_assert_eq!(popped_node, OpenTask::Ignore);
}
pub fn push_task(&mut self, key: DepNode) {
if !self.opened_once.insert(key) {
bug!("Re-opened node {:?}", key)
}
self.task_stack.push(OpenTask::Regular {
node: key,
reads: Vec::new(),
read_set: FxHashSet(),
});
}
pub fn pop_task(&mut self, key: DepNode) -> DepNodeIndex {
let popped_node = self.task_stack.pop().unwrap();
if let OpenTask::Regular {
node,
read_set: _,
reads
} = popped_node {
debug_assert_eq!(node, key);
let target_id = self.get_or_create_node(node);
for read in reads.into_iter() {
let source_id = self.get_or_create_node(read);
self.edges.insert((source_id, target_id));
}
target_id
} else {
bug!("pop_task() - Expected regular task to be popped")
}
}
pub fn push_anon_task(&mut self) {
self.task_stack.push(OpenTask::Anon {
reads: Vec::new(),
read_set: FxHashSet(),
});
}
pub fn pop_anon_task(&mut self, kind: DepKind) -> DepNodeIndex {
let popped_node = self.task_stack.pop().unwrap();
if let OpenTask::Anon {
read_set: _,
reads
} = popped_node {
let mut fingerprint = Fingerprint::zero();
let mut hasher = StableHasher::new();
for read in reads.iter() {
mem::discriminant(&read.kind).hash(&mut hasher);
// Fingerprint::combine() is faster than sending Fingerprint
// through the StableHasher (at least as long as StableHasher
// is so slow).
fingerprint = fingerprint.combine(read.hash);
}
fingerprint = fingerprint.combine(hasher.finish());
let target_dep_node = DepNode {
kind,
hash: fingerprint,
};
if let Some(&index) = self.indices.get(&target_dep_node) {
return index;
}
let target_id = self.get_or_create_node(target_dep_node);
for read in reads.into_iter() {
let source_id = self.get_or_create_node(read);
self.edges.insert((source_id, target_id));
}
target_id
} else {
bug!("pop_anon_task() - Expected anonymous task to be popped")
}
}
/// Indicates that the current task `C` reads `v` by adding an
/// edge from `v` to `C`. If there is no current task, has no
/// effect. Note that *reading* from tracked state is harmless if
/// you are not in a task; what is bad is *writing* to tracked
/// state (and leaking data that you read into a tracked task).
pub fn read(&mut self, source: DepNode) {
match self.task_stack.last_mut() {
Some(&mut OpenTask::Regular {
node: target,
ref mut reads,
ref mut read_set,
}) => {
if read_set.insert(source) {
reads.push(source);
if cfg!(debug_assertions) {
if let Some(ref forbidden_edge) = self.forbidden_edge {
if forbidden_edge.test(&source, &target) {
bug!("forbidden edge {:?} -> {:?} created", source, target)
}
}
}
}
}
Some(&mut OpenTask::Anon {
ref mut reads,
ref mut read_set,
}) => {
if read_set.insert(source) {
reads.push(source);
}
}
Some(&mut OpenTask::Ignore) | None => {
// ignore
}
}
}
pub fn read_index(&mut self, source: DepNodeIndex) {
let dep_node = self.nodes[source.index()];
self.read(dep_node);
}
pub fn query(&self) -> DepGraphQuery {
let edges: Vec<_> = self.edges.iter()
.map(|&(i, j)| (self.id(i), self.id(j)))
.collect();
DepGraphQuery::new(&self.nodes, &edges)
}
#[inline]
pub fn add_edge(&mut self, source: DepNode, target: DepNode) {
let source = self.get_or_create_node(source);
let target = self.get_or_create_node(target);
self.edges.insert((source, target));
}
pub fn add_node(&mut self, node: DepNode) -> DepNodeIndex {
self.get_or_create_node(node)
}
#[inline]
fn get_or_create_node(&mut self, dep_node: DepNode) -> DepNodeIndex {
let DepGraphEdges {
ref mut indices,
ref mut nodes,
..
} = *self;
*indices.entry(dep_node).or_insert_with(|| {
let next_id = nodes.len();
nodes.push(dep_node);
DepNodeIndex::new(next_id)
})
}
}